tojsonl: Failed to infer field types

[datatraveller1]

First of all, thank you very much to jqnatividad for the great tool!

I want to convert CSV to JSON.
command:
qsv tojsonl file.csv -o file.json

e.g. file.csv with content:

col1,col2,col3
a,b,c
d,e,f

However, with this (and any other) file I get:
Failed to infer field types: qsv stats exited with code: 2
Am I doing something wrong?

Expected output file.json:

[
    {
        "col1": "a",
        "col2": "b",
        "col3": "c"
    },
    {
        "col1": "d",
        "col2": "e",
        "col3": "f"
    }
]